Electrophoresis is a widely known technique for separation of biomolecules such as nucleic acid or proteins. Generally, electrophoresis is understood as being migration of charged molecules through a sieving material while an electrical field is applied to said material. According to their different electrophoretic mobility, and, hence, their velocity within said sieving material, a mixture of differently sized and electrically charged molecules becomes separated into fractions of molecules having the same mobility. Said electrophoretic mobility is a physical-chemical function of the molecule in the respective medium, it depends on a plurality of chemical, electrochemical and physical factors such as the aforementioned size and charge of molecules, and further on the characteristics of the carrier material such as pore width. The sieving material may be a gel or a liquid.
Selection of a suitable sieving matrix permits an optimized separation of biomolecules having different biochemical properties: Agarose is a preferred sieving material to perform separation of DNA, whereas protein separation is often carried out in, e.g., polyacrylamide. Analysis of an unknown sample further comprises calibration using a standard detection, particularly optical detection. Said last detection technique is favored due to its reliability, rapidity and direct-to-apply option. Optical detection of biomolecules requires visualization of the separated fractions, which is conveniently done using a staining substance for the molecules to be visualized. Due to physical and chemical properties of said staining substances which are generally suitable for staining specific biochemical molecules, said staining substances are not sufficiently reliable in staining the whole range of components comprised in one single sample similarly. Typical staining substances for nucleic acids like DNA and RNA are intercalating dyes. A plurality of works has been dedicated to perform highly sophisticated electrophoresis.
U.S. Pat. No. 6,835,773 B2 to M. Kratzmeier, e.g., is focusing on electrophoretical analysis of proteins: A minute sample of proteins is introduced in an electrophoresis medium which comprises N-methylurea and a polyacrylamide gel, which is adapted do be subjected to an electrical field being applied across the medium.